Cam drive system for an engine

ABSTRACT

Methods and systems are provided for a cam drive system of an engine. In one example, a front end of an engine includes an idler gear assembly including an idler gear and idler pulley, the idler gear in meshing engagement with a first end of a crankshaft and the idler pulley coupled to and sharing a rotational axis with the idler gear. The front end of the engine may further include first and second camshaft pulleys positioned vertically above the idler gear assembly and a cam drive belt contacting each of the first and second camshaft pulleys and the idler pulley.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional PatentApplication No. 62/327,943 entitled “CAM DRIVE SYSTEM FOR AN ENGINE,”filed on Apr. 26, 2016. The entire contents of the above-referencedapplication are hereby incorporated by reference in its entirety for allpurposes.

FIELD

The present description relates generally to methods and systems for acam drive system of an engine.

BACKGROUND/SUMMARY

Packaging space for an engine within a vehicle may be limited. Inparticular, a height, length, and/or width of an engine may be limitedby a size of the vehicle. However, the large number of enginecomponents, particularly for a diesel engine, may be difficult to fitwithin a frame of smaller vehicles. For example, the front end of anengine may include a plurality of drive mechanisms for driving enginecomponents using rotational energy from a crankshaft of the engine. Inparticular, camshafts may be driven by camshaft pulleys that arerotationally coupled to a crankshaft directly through a drive belt.However, the inventors herein have recognized that coupling the camshaftpulleys directly to the crankshaft via a belt increases the size of thepulleys needed to maintain a desired gear ratio between the crankshaftand the camshafts. Thus, due to the increased size of the camshaftpulleys, such systems increase the overall height and/or width of theengine.

In one example, the issues described above may be addressed by a frontend of an engine comprising, a first end of a crankshaft, an idler gearassembly including an idler gear and an idler pulley, the idler gear inmeshing engagement with the first end of the crankshaft and the idlerpulley coupled to and sharing a rotational axis with the idler gear,first and second camshaft pulleys positioned vertically above the idlergear assembly, and a cam drive belt contacting each of the first andsecond camshaft pulleys and the idler pulley. In this way, by couplingthe camshaft pulleys to the idler gear, the size of the camshaft pulleysmay be reduced, and thus the size of the engine system maycorrespondingly be reduced as well.

In another representation, a method for an engine may comprisetransmitting rotational motion from a crankshaft to an idler gear, theidler gear meshing with a first end of the crankshaft via a plurality ofinterlocking teeth, rotating an idler pulley directly coupled with theidler gear via rotation of the idler gear, the idler gear and idlerpulley sharing a rotational axis, and driving rotation of first andsecond camshaft pulleys through a cam drive belt driven by the idlerpulley, the cam drive belt contacting an outer surface of the first andsecond camshaft pulleys and the idler pulley.

In yet another representation, a system for an engine may comprise afront end, comprising: a first end of a crankshaft, an idler gearassembly including an idler gear and idler pulley, the idler gear inmeshing engagement with the first end of the crankshaft and the idlerpulley coupled to and sharing a rotational axis with the idler gear,first and second camshaft pulleys coupled to first and second camshafts,respectively, and a cam drive belt contacting each of the first andsecond camshaft pulleys and the idler pulley and not the first end ofthe crankshaft, and a back end arranged opposite the front end, the backend including a flywheel coupled to a second end of the crankshaft. Insome examples, the idler gear may include more teeth than the first endof the crankshaft. Additionally or alternatively, the idler gear maycomprise a larger diameter than the first end of the crankshaft.

Thus, the idler gear may rotate at a slower rate than the crankshaft dueto its greater number of teeth and larger diameter. As such, by couplingthe camshaft pulleys to the slower rotating idler gear, the diameter ofthe camshaft pulleys may be reduced. By reducing the size of thecamshaft pulleys, the overall size of the engine system may be reduced.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front perspective view of an example engine system, inaccordance with one or more embodiments of the present disclosure.

FIG. 2 shows a rear perspective view of the example engine system ofFIG. 1, in accordance with one or more embodiments of the presentdisclosure.

FIG. 3 shows a side view of the example engine system of FIG. 1, inaccordance with one or more embodiments of the present disclosure.

FIG. 4 shows a cross-sectional perspective view of a front end of theexample engine system of FIG. 1, including a gear driven diesel fuelinjection pump, in accordance with one or more embodiments of thepresent disclosure.

FIG. 5 shows a cross-sectional view of a front end of the example enginesystem of FIG. 1, including the gear driven diesel fuel injection pumpof FIG. 4, in accordance with one or more embodiments of the presentdisclosure.

FIG. 6 shows a cross-sectional view of a side of the example enginesystem of FIG. 1, including the gear driven diesel fuel injection pumpof FIGS. 4-5, in accordance with one or more embodiments of the presentdisclosure.

FIG. 7 shows a perspective view of the gear driven diesel fuel injectionpump of FIGS. 4-6, in accordance with one or more embodiments of thepresent disclosure.

FIG. 8 shows a cross-sectional perspective view of the front end of theexample engine system of FIG. 1, including the gear driven diesel fuelinjection pump of FIGS. 4-7, in accordance with one or more embodimentsof the present disclosure.

FIG. 9 shows a cross-sectional view of a cylinder head of the exampleengine system of FIG. 1 and illustrates example flow paths of enginecoolant and engine exhaust gases through the cylinder head.

FIG. 10 shows an exhaust gas recirculation (EGR) cooler included by theexample engine system of FIG. 1.

FIG. 11 shows a first cross-sectional view of the EGR cooler included bythe example engine system of FIG. 1.

FIG. 12 shows a second cross-sectional view of the EGR cooler includedby the example engine system of FIG. 1.

FIG. 13 shows a cross-sectional view of an intake manifold included bythe example engine system of FIG. 1.

FIG. 14 shows a cross-sectional view of two cylinders included by theexample engine system of FIG. 1.

FIG. 15 shows a partial view of the example engine system of FIG. 1 andillustrates a relative arrangement of two fuel injectors coupled to theengine system.

FIG. 16 shows a group of fuel injectors configured to couple with theexample engine system of FIG. 1, with the group of fuel injectorsincluding the two fuel injectors shown by FIG. 15.

FIG. 17 shows a fluid-routing gasket coupled to an exhaust manifold ofthe example engine system of FIG. 1.

FIG. 18 shows an enlarged view of a fuel pump of the example enginesystem of FIG. 1.

FIGS. 1-18 are drawn to scale, though other relative dimensions may beused.

DETAILED DESCRIPTION

The following description relates to systems and methods formechanically driving a diesel fuel injection pump and for driving one ormore camshafts of an engine system. A diesel engine, such as the examplediesel engine shown by FIGS. 1-8 and described herein with reference toFIGS. 1-18, may be powered by diesel fuel. The engine may include anexhaust gas recirculation (EGR) system having a plurality of passagesformed within a cylinder head of the engine for flowing coolant andexhaust gases to an EGR valve assembly, as shown by FIG. 9. The EGRvalve assembly is configured to direct coolant and exhaust gases to anEGR cooler including a bypass passage coupled to a baffle, as shown byFIGS. 10-12. The baffle may route gases from the bypass passage to anoutlet of the EGR cooler and reduce a likelihood of gases from thebypass passage recirculating within the EGR cooler. The engine mayadditionally include an intake manifold having helical intake runnersand non-helical intake runners positioned in an alternating arrangement(as shown by FIGS. 13-14) to increase a swirl of intake air within thecombustion chambers. Fuel injectors of the engine may be positioned atdifferent angles relative to each other (as shown by FIGS. 15-16) inorder to shape a spray pattern from each fuel injector to accommodatethe increased amount of swirl of the intake air. An exhaust manifold ofthe engine may include a heat-shielding gasket including a plurality ofchannels shaped to route fluid (e.g., oil leaks) away from an exteriorof the exhaust manifold as shown by FIG. 17.

The engine may include a diesel fuel pump for pumping the fuel tocombustion chambers of the engine. The pump may be driven by the engine.In particular, energy output from combustion of the fuel in thecombustion chambers may be used to drive rotational motion of acrankshaft, which may then be used to power the fuel pump. As shown inthe examples of FIGS. 4-8, the crankshaft may include a gear at a firstend of the crankshaft, proximate to or at a front end of the engine. Thecrankshaft gear may be in meshing engagement with an idler gear of anidler gear assembly such that rotational motion of the crankshaft drivesrotational motion of the idler gear. The idler gear may be positionedbetween the crankshaft gear and a gear of an input shaft of the fuelpump, and may be in meshing engagement with both. In this way,rotational motion of the crankshaft may be transferred to the fuel pumpvia the idler gear, where rotational motion of the crankshaft may betransferred to the idler gear, which is then transferred to the inputshaft of the fuel pump. Rotational motion of the input shaft of the fuelpump may drive a piston of the fuel pump, which pressurizes fueldelivered to the combustion chambers. Thus, the fuel pump may be drivenby one or more gears, and not by a belt or chain. In some examples, thefuel pump may be driven by a gear assembly including one or more scissorgears, as shown by FIG. 18. Additionally, driving the fuel pump via thegear drive system may reduce drive torque irregularities (e.g., such asthose that occur with a belt driven system) and the resulting wear oncomponents of the fuel pump, thereby increasing the longevity of thefuel pump.

The example engine described above and shown in FIGS. 1-8, may includecamshafts which rotate to regulate opening and closing times of intakeand exhaust valves of combustion chambers of the engine. Rotation of thecamshafts may be driven by the crankshaft of the engine at a particulargear ratio to maintain a desired angular speed ratio between thecamshafts and the crankshaft. In one example the desired angular speedratio may be approximately 2:1 such that the camshafts complete one fullrotation for approximately every two full rotations of the crankshaft.

The camshafts may be coupled to the idler gear assembly via a belt andrespective pulleys, where the idler gear assembly is driven directly bythe crankshaft via meshing teeth. Thus, the idler gear assembly maytransmit torque from the crankshaft to the camshafts. As shown in theexamples of FIGS. 4-8, the idler gear assembly may include more teeththan a first end of the crankshaft with which it is in meshingengagement. Thus, the idler gear assembly may rotate at a slower ratethan the crankshaft. Due to the slower angular velocity of the idlergear assembly, the size of camshaft pulleys coupling the camshafts tothe idler gear assembly may be reduced while maintaining the desiredangular speed ratio between the camshafts and the crankshaft. As such,by reducing the size of the camshaft pulleys, the overall size of theengine may be reduced.

FIGS. 1-18 show the relative positioning of various components of anengine system. If shown directly contacting each other, or directlycoupled, then such components may be referred to as directly contactingor directly coupled, respectively, at least in one example. Similarly,components shown contiguous or adjacent to one another may be contiguousor adjacent to each other, respectively, at least in one example. As anexample, components lying in face-sharing contact with each other may bereferred to as in face-sharing contact or physically contacting oneanother. As another example, elements positioned apart from each otherwith only a space there-between and no other components may be referredto as such, in at least one example.

As yet another example, elements shown above/below one another, atopposite sides to one another, or to the left/right of one another maybe referred to as such, relative to one another. Further, as shown inthe figures, a topmost element or point of element may be referred to asa “top” of the component and a bottommost element or point of theelement may be referred to as a “bottom” of the component, in at leastone example.

Further, FIGS. 1-18 include an axis system 150, which may be used todescribe the relative positioning of components of the engine system.The axis system 150 may include a vertical axis 152, a lateral axis 154,and a longitudinal axis 156. The axes 152, 154, and 156 may beorthogonal to one another, thereby defining a three-dimensional axissystem. As used herein, “top/bottom”, “upper/lower”, “above/below”, maybe relative to the vertical axis 152 and may be used to describe thepositioning of elements of the figures relative to one another along thevertical axis 152. Similarly, “to the left/right of,” and “to the sideof” may be used to describe the positioning of elements of the figuresrelative to one another along the lateral axis 154 and may be used todescribe the positioning of elements of the figures relative to oneanother along the lateral axis 154. Further, “in front of,” and “behind”may be relative to the longitudinal axis 156 and may be used to describethe positioning of element of the figures relative to one another alongthe longitudinal axis 156.

As such, elements shown above other elements are positioned verticallyabove the other elements, in one example. As yet another example, shapesof the elements depicted within the figures may be referred to as havingthose shapes (e.g., such as being circular, straight, planar, curved,rounded, chamfered, angled, or the like). Further, elements shownintersecting one another may be referred to as intersecting elements orintersecting one another, in at least one example. Further still, anelement shown within another element or shown outside of another elementmay be referred to as such, in one example.

Beginning with FIG. 1, it shows a front perspective view 100 of anexample engine system 10. The engine system 10 may include a front end102 opposite a back end 104, a top 106 opposite a bottom 108, and afirst side 110 opposite a second side 112. The engine system 10 includesa cylinder head 114 coupled to a cylinder block 116, forming one or morecombustion chambers 118 (which may be referred to herein as cylinders).Specifically, the combustion chambers 118 may be formed via one or morebores in the cylinder block 116, where the bores define the side andbottom walls of the combustion chambers 118. The cylinder head 114 maybe positioned vertically above the cylinder block 116, and a bottomsurface of the cylinder head 114 that interfaces with a top surface ofthe cylinder block 116 may define the top wall of the combustionchambers 118. In the examples described herein with reference to FIGS.1-18, the engine system 10 includes four combustion chambers 118.However, it should be appreciated that in other examples, the enginesystem 10 may include more or less than four combustion chambers 118.Further, in the description herein, combustion chambers 118 may also bereferred to herein as cylinders 118.

The cylinders 118 may be arranged adjacent and/or parallel to oneanother along the longitudinal axis 156, in what is commonly referred toby those skilled in the art as “inline” arrangement. Thus, the cylinders118 may be arranged as a single row of cylinders. However, it should beappreciated that in other examples, the engine cylinders 118 may bearranged in multiple rows such as in a “V” type configuration.

A crankcase skirt 119 may be positioned below the cylinder block 116,between the cylinder block 116 and an oil pan 120. Thus, the crankcaseskirt 119 may be coupled to the bottom of the cylinder block 116, andthe oil pan 120 may be coupled to the bottom of the crankcase skirt 119.As such, the oil pan 120 may define the bottom 108 of the engine system10. Said another way, the oil pan 120 may be positioned at the bottom108 of the engine system 10. The oil pan 120 may house an oil pump (notshown in FIG. 1) which pumps oil to various rotating engine componentsfor lubrication thereof.

Intake air may enter the engine system 10 via an intake conduit 122. Theintake air may then be routed to the combustion chambers 118 via anintegrated intake manifold 422 (shown by FIG. 4, FIG. 8, and FIG. 13 anddescribed below in further detail below with reference to FIG. 13). Inparticular, an amount of airflow to the combustion chambers 118 may beregulated by an intake throttle and/or one or more intake valves. Uponopening of the one or more intake valves, the intake air may beintroduced into the combustion chambers 118, such as during an intakestroke of a piston. The intake air may then be compressed during acompression stroke of the piston as the piston translates upwardstowards the cylinder head 114 and top dead center (TDC) position. Dieselfuel may be injected into each of the combustion chambers 118 viarespective fuel injectors 124 positioned above the combustion chambers118. In particular, diesel fuel may be injected directly into each ofthe cylinders 118 by the fuel injectors 124. The injected fuel maycombust with the compressed intake air during a subsequent power stroke.After combustion, one or more exhaust valves 126 may open to permit theproducts of combustion to exit the combustion chambers 118 to an exhaustmanifold 128.

The exhaust manifold 128 may couple the combustion chambers 118 to acommon exhaust passage 130 for routing the products of combustion fromthe combustion chambers 118 to the exhaust passage 130. One or more ofthe combustion chambers 118 may be additionally coupled to an internalexhaust passage 902 formed by interior surfaces of the cylinder head 114in order to route exhaust gases to an EGR assembly 900 coupled to theengine system 10 (as shown by FIG. 9 and described in further detailbelow). The exhaust passage 130 may include a turbine 131 of aturbocharger of the engine system 10. The turbine 131 may be coupled toan intake compressor positioned in the intake conduit 122 forcompressing the intake air delivered to the combustion chambers 118.After flowing through the turbine 131, exhaust gasses may pass through adiesel particular filter and/or other emissions control devices beforebeing emitted to the environment.

Combustion of the air-fuel mixture in the combustion chambers 118 maydrive translational movement of the pistons positioned within thecombustion chambers 118. Movement of the pistons may be converted intorotational motion of a crankshaft 132 which may be used to providetorque to one or more vehicle wheels. In particular, a flywheel 134 maybe coupled to a rear, second end of the crankshaft 132, opposite afront, first end 133 of the crankshaft 132, at the back end 104 of theengine system 10, as shown below with reference to FIG. 2. The front,first end 133 of the crankshaft 132 may be positioned at or proximate tothe front end 102 of the engine system 10, and may include one or moregears and/or pulleys for driving various components of the engine system10. For example, as shown in FIG. 1, the crankshaft 132 may include oneor more outer first pulleys 136. One of the outer first pulleys 136 maybe coupled to a water pump pulley 138 via a belt or chain for powering awater pump 140 of the engine system 10. In particular the water pumppulley 138 may be coupled to the water pump 140, such that rotationalmotion of the pulley 138 powers the water pump 140. The outer firstpulleys 136 may include additional pulleys which may be coupled viabelts and/or chains to various other engine components such as an A/Ccompressor to transfer power from the crankshaft thereto. The water pump140 may supply water or coolant to one or more of the cylinder head 114,cylinder block 116, and a radiator to cool various components of theengine system 10.

The engine system 10 may include a front cover 141 at the front end 102that protects and covers interior components of the engine system 10 atthe front end 102. The outer first pulleys 136 and water pump pulley 138are shown positioned in front of, or exterior to, the front cover 141.Interior to the front cover 141, and as described below in greaterdetail with reference to FIGS. 4-8, the crankshaft 132 may be coupled toone or more gears and/or belts to drive rotational motion of an intakecamshaft pulley 142 and an exhaust camshaft pulley 144. The pulleys 142and 144 may be positioned adjacent to one another at or proximate thetop 106 of the front end 102 of the engine system 10 relative to thevertical axis 152. Further, the crankshaft 132 may include a gear at thefront, first end 133 that may be in meshing engagement with an idlergear (described below with reference to FIGS. 4-8), the idler gearincluding a pulley coupled to the camshaft pulleys 142 and 144 via acamshaft drive belt 146. The idler gear may be positioned behind andinterior to the outer first pulleys 136 relative to the front end 102.The camshaft pulleys 142 and 144 may be coupled to separate camshafts.In the example of FIG. 1, only an exhaust camshaft 148 is shown. Thecamshafts may thus rotate with the camshaft pulleys 142 and 144, and mayregulate the opening and closing timing of the intake and exhaustvalves. In particular, the intake camshaft pulley 142 may be coupled toan intake camshaft along the same rotational axis as the intake camshaftand may regulate the opening and closing times of one or more intakevalves. Similarly, the exhaust camshaft pulley 144 may be coupled to anexhaust camshaft along the same rotational axis as the exhaust camshaftpulley 144 and may regulate opening and closing times of the exhaustvalves 126. Thus, the exhaust camshaft may rotate at approximately thesame rotational speed as the exhaust camshaft pulley 144, and the intakecamshaft may rotate at approximately the same rotational speed as theintake camshaft pulley 142. The camshaft 148 may include camshaft lobes149 which translate rotational motion of the camshaft 148 into linearmotion of the exhaust valves.

As shown in the example of FIG. 1, the camshaft 148 may be positionedvertically above the cylinder block 116 in the cylinder head 114. Assuch, the camshaft 148 may be positioned vertically above the crankshaft132. Although only two camshafts are shown in the example of FIG. 1, itshould be appreciated that more or less than two camshafts may beincluded in other examples. Further, in some examples, the engine system10 may include a variable valve timing system or variable cam timingsystem to adjust valve opening and/or closing times.

Moving on to FIG. 2, it shows a back perspective view 200 of the enginesystem 10. Specifically, FIG. 2 shows a more detailed view of the backend 104 of the engine system 10, including the flywheel 134. Theflywheel 134 may be coupled to the crankshaft 132 at a rear, second end233 of the crankshaft 132, the rear, second end 233 opposite the front,first end 133 (not shown in FIG. 2). Thus, the flywheel 134 may becoupled to the crankshaft 132 at the back end 104 of the engine system10. The flywheel 134 may couple the crankshaft 132 to a vehicletransmission, for transmitting torque from the crankshaft 132 to thetransmission and one or more vehicle wheels.

FIG. 2 also shows an example of one or more pistons 202 positionedwithin one of the combustion chambers 118. The pistons 202 may translateup and down along the vertical axis 152 between TDC and bottom deadcenter (BDC) positions.

Continuing to FIG. 3, it shows a first side view 300 of the enginesystem 10 facing the first side 110 of the engine system 10. Cutaways oftwo of the combustion chambers 118 are shown, exposing two of thepistons 202 positioned therein. Further, the fuel injectors 124 areshown positioned above the combustion chambers 118, such that each ofthe combustion chambers 118 includes a dedicated fuel injector. The fuelinjectors 124 may be coupled to a fuel pump via fuel supply lines 302.Thus, the fuel supply lines 302 may be coupled to the fuel injectors 124on a first end, and on an opposite second end to a fuel pump (not shownin FIG. 3).

Turning now to FIGS. 4 and 5, they show cross-sectional views 400 and500 respectively, of the engine system 10 at the front end 102 of theengine system 10, where the front cover 141 (described above withreference to FIG. 1) is removed. Thus, FIGS. 4 and 5 may be describedtogether in the description herein. Thus, the cross-section of theengine system 10 shown in FIG. 4 is taken at the front end 102 of theengine system 10 along a plane parallel to the plane defined by thevertical axis 152 and lateral axis 154. The front cover 141 has beenremoved, exposing interior components of the engine system 10 at thefront end 102 of the engine system 10. Thus, the components of theengine system 10 shown in FIG. 4, may be immediately adjacent andinterior to the front cover 141 and outer first pulleys 136 describedabove with reference to FIGS. 1 and 3.

The first end 133 of the crankshaft 132 may include one or more of acrankshaft gear 402 and an oil pump pulley 403. The crankshaft gear 402and oil pump pulley 403 may be coupled to the crankshaft 132 and mayshare a rotational axis with the crankshaft 132. In particular, thepulley 403 and gear 402 may be rotationally fixed relative to thecrankshaft 132. The oil pump pulley 403 may also be referred to hereinas oil pump drive gear 403. Thus, the pulley 403 and gear 402 may rotatewith and at substantially the same angular velocity as the crankshaft132. Thus, the oil pump pulley 403 and crankshaft gear 402 may beconcentrically positioned around a central rotational axis of thecrankshaft 132. The crankshaft gear 402 may be coupled to an idler gearassembly 404. The oil pump pulley 403 may be coupled to an oil pump (notshown in FIG. 4) positioned in the oil pan 120 via oil pump belt 405.Thus, rotational motion of the crankshaft 132 may be transferred to theoil pump via belt 405 to drive and power the oil pump.

The crankshaft gear 402 may drive the idler gear assembly 404 viameshing engagement between a plurality of teeth of the crankshaft gear402, and a plurality of teeth 407 of the idler gear assembly 404. Inparticular, the idler gear assembly 404 may include an idler gear 406and idler pulley 408, where the idler gear 406 includes the teeth 407.Thus, the idler gear 406 is in meshing engagement with the first end 133of the crankshaft 132. The idler gear 406 and idler pulley 408 mayintegrally form the idler gear assembly 404. Thus, in some examples theidler gear assembly 404 may comprise a single continuous piece thatincludes the idler gear 406 and idler pulley 408. The idler gear 406,idler pulley 408, and idler gear assembly 404 may thus share a commonrotational axis. Further, the idler gear 406, idler pulley 408, andidler gear assembly 404 may be rotationally fixed with one another, suchthat they rotate in the same direction and at substantially the sameangular velocity. The idler gear 406 may have a larger diameter than theidler pulley 408. Thus, for a given angular velocity of the idler gearassembly 404, the edges or teeth 407 of the idler gear 406 may have agreater linear speed than the edges of the pulley 408, due to the largerdiameter of the idler gear 406.

As the crankshaft 132 and thus crankshaft gear 402 rotate, the meshingteeth of the crankshaft gear 402 and idler gear 406 may cause the idlergear assembly 404 to rotate. Thus, the idler gear assembly 404 may bedriven by the turning crankshaft 132 via meshing engagement of the teethof the idler gear 406 and crankshaft gear 402. The idler gear assembly404 may rotate in a direction opposite that of the crankshaft 132. Thus,the crankshaft 132 may rotate in a first direction, and the idler gearassembly 404 rotates in a second direction, the second directionopposite the first direction. For example, if the crankshaft 132 rotatesin a counter-clockwise direction as viewed from the front end 102 of theengine system 10, the idler gear assembly 404 rotates in the clockwisedirection.

Further, the idler gear 406 and idler gear assembly 404 may rotate at aslower rate (smaller angular velocity) than the crankshaft gear 402 andcrankshaft 132. In particular, the idler gear 406 may include more teeththan the crankshaft gear 402 and/or may comprise a larger diameter thanthe crankshaft gear 402, and thus may rotate more slowly than thecrankshaft 132 when driven by the crankshaft gear 402. In one example,the idler gear 406 may include 63 teeth and the crankshaft gear 402 mayinclude 45 teeth. In other examples, the idler gear 406 may include moreor less than 63 teeth and/or the crankshaft gear 402 may include more orless than 45 teeth.

Further, in some examples, the spacing of the crankshaft gear teeth, andthe idler gear teeth and/or the sizing of the teeth may be approximatelythe same to reduce slippage between the gears 402 and 406 and maintainmeshing engagement between the two gears 402 and 406. Thus, in suchexamples, the idler gear 406 may have a larger diameter than thecrankshaft gear 402 to accommodate its larger number of teeth. The idlergear 406 may additionally or alternatively be sized to separate theidler gear 406 and a fuel pump drive gear 412 with which it is also inmeshing engagement. Thus, the idler gear 406 may be sized based on oneor more of a desired distance between the crankshaft gear 402 and thefuel pump drive gear 412, a desired number of teeth of teeth on theidler gear 406, a number of teeth on the crankshaft gear 402, a desiredgear or speed ratio between the idler gear 406 and the crankshaft gear402, etc.

However, in other examples, the crankshaft gear 402 may have a largerdiameter than the idler gear 406. Further, in some examples, the spacingand/or sizing of the crankshaft gear teeth and idler gear teeth may bedifferent. In yet further examples, the crankshaft gear 402 may comprisemore teeth than the idler gear 406 and/or may rotate at a slower ratethan the crankshaft gear 402.

The idler gear 406 may also be in meshing engagement with the fuel pumpdrive gear 412 via a plurality of interlocking teeth. Specifically,teeth 407 of the idler gear 406, and teeth 414 of the fuel pump drivegear 412 may be in meshing engagement such that rotational motion of theidler gear assembly 404 drives rotational motion of the fuel pump drivegear 412. The fuel pump drive gear 412 may be coupled to and may share arotational axis with an input shaft 415 of a fuel pump 416. In someexamples, the fuel pump drive gear 412 and the input shaft 415 may berotationally fixed, such that they rotate at substantially the sameangular velocity. The input shaft 415 may drive a piston or otherpressurization element of the pump 416. In one example the pump 416 mayinclude a single plunger (e.g., piston) as described below. However, inother examples, the pump 416 may include more than one plunger orpressurization element, and each plunger or pressurization element maybe driven by the rotation of the input shaft 415.

Thus, rotational motion of the input shaft 415 may be used to power thepump 416, displace the piston of the pump 416, and thus pressurize fueldelivered to the combustion chamber 118 (not shown in FIG. 4). In someexamples, the piston of the pump 416 may move linearly up and down(e.g., from a top-dead-center position to a bottom-dead-center position,and from the bottom-dead-center position to the top-dead-centerposition) twice for every one complete turn (e.g., 360 degree rotation)of the crankshaft 132. In this way, the crankshaft 132 may be used topower the pump 416. Specifically, rotational motion of the crankshaft132 may be transferred to the input shaft 415 of the pump 416 via theidler gear 406 and fuel pump drive gear 412 to produce the linear motionof the piston within the pump 416.

Thus, the idler gear 406 and idler gear assembly 404 may be positionedbetween and may separate the crankshaft 132 and the fuel pump drive gear412. Further, the idler gear assembly 404 may be positioned verticallyabove the crankshaft 132. Thus, the idler gear 406 may be in meshingengagement with the first end 133 of the crankshaft 132 and with thefuel pump drive gear 412 via the plurality of interlocking teeth.Further, the crankshaft 132, and in particular the crankshaft gear 402,may not be in meshing engagement with the fuel pump drive gear 412.Thus, the crankshaft gear 402, and fuel pump drive gear 412 may beseparated by the idler gear 406. As such, the crankshaft 132 and fuelpump drive gear 412 may not be in physical contact with one another.However, torque may still be transmitted between the crankshaft 132 andthe fuel pump drive gear 412 via the idler gear 406 (e.g., from thecrankshaft 132 to the fuel pump drive gear 412 via the idler gear 406).

The fuel pump drive gear 412 may have approximately the same diameterand/or number of teeth as the crankshaft gear 402. Thus, in suchexamples, the fuel pump drive gear 412 may have a smaller diameter thanthe idler gear 406 and may include approximately 45 teeth. Further, thefuel pump drive gear 412 may rotate at approximately the same angularspeed as the crankshaft 132. However, in other examples, the fuel pumpdrive gear 412 may have a larger or smaller diameter than the crankshaftgear 402, may include more or less teeth than the crankshaft gear 402,and/or may rotate at a different angular speed than the crankshaft 132.Further, the fuel pump drive gear 412 rotates in the opposite directionof the idler gear 406. Thus, the fuel pump drive gear 412 rotates in thesame direction as the crankshaft 132.

In this way, side loading of the fuel pump input shaft 415 (e.g., forcesagainst the fuel pump input shaft 415 in radial directions relative to arotational axis of the fuel pump input shaft 415) and fuel pump bearingsmay be reduced relative to systems where belts and pulleys are used tocouple the crankshaft 132 to the fuel pump input shaft 415, by includingthe idler gear 406 as a torque transferring mechanism between thecrankshaft 132 and the fuel pump input shaft 415. Further, frictionallosses incurred between fuel pump 416 and crankshaft 132 may be reducedrelative to systems where belts and pulleys are used to couple thecrankshaft 132 to the fuel pump input shaft 415 by coupling thecrankshaft 132 to the fuel pump input shaft 415 via the idler gearassembly 404. As such, friction and wear on the fuel pump 416 may bereduced, and a longevity of the fuel pump 416 may be increased byreducing the load on one or more bearings of the fuel pump 416. Furtherstill, a distance between the crankshaft 132 and the fuel pump 416 maybe reduced by including the idler gear 406 relative to systems wherebelts and pulleys are used to couple the crankshaft 132 to the fuel pump416, thus reducing the size, packaging, and cost of the engine system10.

The camshaft drive belt 146 may be driven by the idler gear assembly404. Specifically, the camshaft drive belt 146 may contact an outercircumferential surface of the idler pulley 408. Thus, the camshaftdrive belt 146 may rotate as the idler gear assembly 404 rotates. Inthis way, the crankshaft 132 may drive the camshaft drive belt 146 viathe idler gear assembly 404. Specifically, the crankshaft 132 drivesrotation of the idler gear assembly 404 via meshing engagement betweenthe first end 133 of the crankshaft 132 and the idler gear 406, androtation of the idler gear 406 drives rotation of the camshaft drivebelt 146 via pulley 408, with the pulley 408 directly coupled to theidler gear 406 such that rotating the idler gear 406 by a first amountof angle (e.g., degrees) rotates the pulley 408 by the same amount ofangle. In this way, the crankshaft 132 may drive rotation of the idlergear assembly 404, and the idler gear assembly 404 may drive rotation ofboth the camshaft drive belt 146, and the fuel pump drive gear 412.However, the camshaft drive belt 146 may not contact (e.g., be inface-sharing contact with) the crankshaft 132.

The camshaft drive belt 146 may additionally couple to outercircumferential surfaces of the camshaft pulleys 142 and 144.Specifically, the camshaft pulleys 142 and 144 may include outer teeth438 that may be in meshing engagement with the camshaft drive belt 146.In some examples, the pulleys 142 and 144 may include approximately 21teeth each. However, in other examples, the pulleys 142 and 144 may eachinclude more or less than 21 teeth. The number of teeth on the pulleys142 and 144 and/or sizing of the pulleys 142 and 144 may be selected toachieve a 2:1 gear ratio between the crankshaft 132 and the pulleys 142and 144, such that the pulleys 142 and 144 and camshafts complete onefull rotation for every two full rotations of the crankshaft 132. A fullrotation may be defined as 360 degrees of rotation. Thus, the camshaftsand pulleys 142 and 144 may rotate 360 degrees for every 720 degreesthat the crankshaft 132 rotates.

Thus, rotation of the idler gear assembly 404 via the rotatingcrankshaft 132 may drive rotation of the camshaft drive belt 146 whichin turn may drive rotation of the camshaft pulleys 142 and 144. Thecamshaft pulleys 142 and 144 may share a rotational axis with thecamshafts. In particular, the intake camshaft pulley 142 may share arotational axis with an intake camshaft 448, and the exhaust camshaftpulley 144 may share a rotational axis with the exhaust camshaft 148.The intake camshaft pulley 142 may be rotationally fixed with the intakecamshaft 448 such that the camshaft pulley 142 and camshaft 448 rotateat approximately the same angular velocity, and/or the exhaust camshaftpulley 144 may be rotationally fixed with the exhaust camshaft 148 suchthat the camshaft pulley 144 and camshaft 148 rotate at approximatelythe same angular velocity. However, in other examples, a variable valvetiming system may be included to adjust the relative speed of thepulleys 142, and 144 and the camshafts 148, and 448 (e.g., increase ordecrease a rotational speed of the camshaft 148 and/or camshaft 448relative to a rotational speed of the pulley 142 and/or the pulley 144,respectively). As shown in the example of FIG. 4, the camshafts 148 and448, and the camshaft pulleys 142 and 144 may be positioned verticallyabove the idler gear assembly 404.

In this way, the belt 146 may couple the idler gear assembly 404 to thecamshaft pulleys 142 and 144. The belt 146 may be directly coupled tothe idler pulley 408 and not coupled to the crankshaft 132. As such,rotational motion of the crankshaft 132 may be transmitted first to theidler gear assembly 404, and then from the idler gear assembly 404 tothe camshaft pulleys 142 and 144 via the belt 146. The belt 146 may forma closed loop around the outer surfaces of the idler pulley 408 and thecamshaft pulleys 142 and 144. As such, the linear speed of the camshaftpulleys 142 and 144 at the outer edges or teeth of the pulleys 142 and144 may be approximately the same as the linear speed of the idlerpulley 408 at the outer surface of the pulley 408. Further, the camshaftpulleys 142 and 144 may rotate in the same direction as the idler gearassembly 404 due to the rotating belt 146 coupling the pulleys 142 and144 to the idler gear assembly 404. As such, the camshaft pulleys 142and 144 may rotate in a direction opposite of the crankshaft. Thus, thecrankshaft 132 may rotate in a first direction, and the idler gearassembly 404 and pulleys 142 and 144 rotate in a second direction, thesecond direction opposite the first direction. For example, if thecrankshaft 132 rotates in a counter-clockwise direction as viewed fromthe front end 102 of the engine system 10, the pulleys 142 and 144rotate in the clockwise direction.

The engine system 10 may further include a tensioner 410. As shown inthe example of FIG. 4, the tensioner 410 may be positioned verticallyabove the idler gear assembly 404. The tensioner 410 may be rotatable,and may be biased to rotate in a direction via a biasing member (e.g., aspring). In the example of FIG. 4, the biasing member of the tensioner410 may bias the tensioner 410 to rotate in a counterclockwise directionwhen viewed from the front end 102 of the engine system 10. As such, thetensioner 410 may exert a lateral force to the left (e.g., in thepositive direction along the lateral axis 154) against the belt 146, andthe belt 146 may correspondingly exert a normal force against thetensioner 410 in a direction opposite to the lateral force (e.g., to theright and in the negative direction along the lateral axis 154). Thelateral force against the belt 146 from the tensioner 410 may tightenthe belt 146 against the pulley 142, the pulley 144, and the idlerpulley 408. In this way, the tensioner 410 may maintain tension in thebelt 146 to an approximately constant amount. The tensioner 410 maycontact an exterior first surface 411 of the belt 146, while the pulleys142 and 144, and the idler pulley 408 may contact an opposite interiorsecond surface 413 of the belt 146.

Due to its larger diameter and/or greater number of teeth relative tothe crankshaft gear 402, the idler gear 406 may rotate at a smallerangular velocity than the crankshaft 132. As such, when coupled to theidler gear assembly 404, the belt 146 may rotate at a lower speed thanit would when coupled to the crankshaft 132. Because the speed of thebelt 146 may be reduced, the diameter of the camshaft pulleys 142 and144 may be reduced in the embodiment of the engine system shown in FIG.4, relative to engine systems where the camshaft belt is directlycoupled to the crankshaft 132, to achieve a desired angular velocityratio between the crankshaft 132 and the camshaft pulleys 142 and 144.For example, the desired angular velocity ratio between the crankshaft132 and the camshaft pulleys 142 and 144 may be approximately 2:1, suchthat the camshaft pulleys 142 and 144 and camshafts 148 and 448 completeapproximately one complete rotation for every two complete rotations ofthe crankshaft 132. However, it should be appreciated that the desiredangular velocity ratio may be greater or less than 2:1 in otherexamples. By reducing the diameter of the camshaft pulleys 142 and 144,the overall size, packaging, and cost of the engine system 10 may bereduced relative to system where the camshaft belt is directly coupledto the crankshaft 132. In some examples, the diameters of the camshaftpulleys 142 and 144 may be approximately the same. However, in otherexamples, the diameters of the camshafts pulleys 142 and 144 may bedifferent.

The engine system 10 may further include an exhaust gas recirculation(EGR) system as shown by FIGS. 9-12 and described below. In particular,the engine system 10 may include a high-pressure exhaust gasrecirculation system, where an exhaust gases flow through an exhaustpassage formed within an interior of the cylinder head, through an EGRassembly and EGR cooler, and to a location downstream of the compressorof the turbocharger in the intake conduit 122. Additionally oralternatively, the engine system 10 may include a low-pressure EGRsystem where a LP-EGR passage couples the exhaust passage downstream ofthe turbine of the turbocharger to a location upstream of the compressorof the turbocharger in the intake conduit 122. In this way, exhaustgases may be recirculated to the intake conduit 122. Intake conduit 122is shown in FIG. 4 to include an intake throttle 418 which may regulatean amount of air flowing into the engine system 10.

EGR passage 420 may couple an EGR cooler 424 to the engine intake.Specifically, in examples where the EGR system is configured as anHP-EGR system, such as in the example of shown by FIG. 4 and FIGS. 9-12,the EGR passage 420 may be coupled to the intake manifold 422. Theintake manifold 422 may be an integrated intake manifold 422. The intakemanifold 422 routes intake gasses from the intake conduit 122 to each ofthe combustion chambers 118 (not shown in FIG. 4). The EGR systemincludes EGR cooler 424 for cooling exhaust gases that are recirculatedto the intake manifold 422. Specifically, the EGR cooler 424 may bepositioned upstream of the EGR passage 420 for cooling the exhaustgasses en route to the intake manifold 422.

Turning now to FIG. 6, it shows a side cross-sectional view 600 of theengine system 10 at the second side 112 of the engine system 10. Thus,the cross-section of the engine system 10 shown in FIG. 6 is taken atthe second side 112 of the engine system 10 along a plane parallel tothe plane defined by the vertical axis 152 and longitudinal axis 156. Assuch, interior components of the engine system 10 at the second side 112of the engine system 10 are exposed (e.g., shown) in FIG. 6.

As depicted in FIG. 6, the water pump pulley 138 may be positioned infront of (e.g., in the negative direction of the longitudinal axis 156from the crankshaft gear 402) the crankshaft gear 402, oil pump belt 405and oil pump pulley 403, etc. Further, the oil pump belt 405 and oilpump pulley 403 may be positioned in front of and adjacent to thecrankshaft gear 402. Thus, the crankshaft gear 402 may be positionedbehind the oil pump belt 405, oil pump pulley 403, and water pump pulley138. However, the crankshaft gear 402, idler gear 406, and fuel pumpdrive gear 412 may be aligned with each other along the longitudinalaxis 156. Thus, the crankshaft gear 402, idler gear 406, and fuel pumpdrive gear 412 may be positioned parallel to each other along a sameplane, with the plane being parallel to a plane defined by the verticalaxis 152 and lateral axis 154. Thus, the rotational axes of the fuelpump drive gear 412, crankshaft gear 402, and idler gear 406 may beparallel to one another (e.g., may extend in a same direction). Bypositioning the gears 402, 412, and 406 in the same plane, the length ofthe engine system 10 with respect to the longitudinal axis 156 may bereduced relative to systems where the pump 416 is driven by a belt orchain. As such, the size, packaging and/or cost of the engine system 10may be reduced.

Further, as depicted in FIG. 6, the fuel pump drive gear 412 and fuelpump 416 may be positioned vertically above the crankshaft 132.Additionally or alternatively, the fuel pump 416 may be positionedbehind the first end 133 of the crankshaft 132, and/or behind thecrankshaft gear 402, idler gear 406, and fuel pump drive gear 412.Further, the fuel pump 416 may be positioned below the intake manifold422 (shown and described above with reference to FIG. 4), and below thecamshaft pulleys 142 and 144. The fuel pump 416 may be positioned belowthe EGR cooler 424.

Further, as depicted in FIG. 6, the idler pulley 408 (obscured from viewin FIG. 6 by the camshaft drive belt 146 which is positioned over theidler pulley 408), oil pump pulley 403, oil pump belt 405, and camshaftdrive belt 146 are all aligned along a same plane at the front end 102of the engine system 10. Thus, the idler pulley 408, oil pump pulley403, oil pump belt 405, and camshaft drive belt 146 may be positionedparallel to each other along the same plane, where the plane is parallelto a plane defined by the vertical axis 152 and lateral axis 154. Saidanother way, the idler pulley 408, oil pump pulley 403, oil pump belt405, and camshaft drive belt 146 may be positioned at a same positionalong the longitudinal axis 156. Further, the rotational axes of theidler pulley 408, oil pump pulley 403, oil pump belt 405, and camshaftdrive belt 146 may be parallel to one another.

FIG. 6 also shows two of the pistons 202 coupled to the crankshaft 132via respective connecting rods 604. The crankshaft 132 may include mainjournals 602, and counterweights 606. The counter weights 606 may reducea magnitude of one or more vibrational modes of the crankshaft 132(e.g., motions of the crankshaft 132 in different directions, atdifferent frequencies, etc.) as the rotational motion of the crankshaft132 is converted into linear motion of the pistons 202.

Turning now to FIGS. 7 and 8, they show side perspective views 700 and800 respectively, of the front end 102 of the engine system 10. Thus,FIGS. 7 and 8 show the components at the front end 102 of the enginesystem 10 shown previously in FIGS. 4 and 5, where the front cover 141has been removed, exposing interior components of the engine system 10at the front end 102. As such, FIGS. 7 and 8 may be described togetherin the description herein.

As depicted in FIG. 8, the camshaft pulleys 142 and 144 may bepositioned vertically above one or more of the fuel pump 416, idler gearassembly 404, tensioner 410, fuel pump drive gear 412, and crankshaft132. Further, the idler pulley, oil pump pulley 403, oil pump belt 405,camshaft drive belt 146, and camshaft pulleys 142 and 144 are allarranged in a common plane at the front end 102 of the engine system 10.Thus, the idler pulley 408, oil pump pulley 403, oil pump belt 405,camshaft drive belt 146, and camshaft pulleys 142 and 144 may bepositioned parallel to each other along a same plane, where the planemay be parallel to a plane defined by the vertical axis 152 and lateralaxis 154. Said another way, the idler pulley 408, oil pump pulley 403,oil pump belt 405, camshaft drive belt 146, and camshaft pulleys 142 and144 may be positioned at the same position along the longitudinal axis156. Further, the rotational axes of the idler pulley 408, oil pumppulley 403, oil pump belt 405, camshaft drive belt 146, and camshaftpulleys 142 and 144 may be parallel to each other.

Further, the fuel pump 416 may be positioned below the intake manifold422. In this way, by coupling the fuel pump 416 to the crankshaft 132via a drive gear (e.g., idler gear 406), the distance between the fuelpump 416 and the crankshaft 132 may be reduced compared to exampleswhere the fuel pump 416 is coupled to the crankshaft 132 via a belt orchain. As such, the fuel pump 416 may be positioned below the camshaftpulleys 142 and 144 instead of above the pulleys 142 and 144 as may bethe case in examples where the fuel pump 416 is driven by a pulley orbelt. As such, the height of the engine system 10 with respect to thevertical axis may be reduced by driving the fuel pump 416 via a drivegear (e.g., idler gear 406) relative to examples where the fuel pump 416is driven by a belt.

FIG. 9 shows a cross-sectional view of the cylinder head 114 andillustrates a flow of exhaust gases and engine coolant through thecylinder head 114 toward an EGR assembly 900. Cylinder head 114 includesa plurality of passages formed within an interior of the cylinder head114. Specifically, cylinder head 114 includes an internal exhaustpassage 902 for flowing exhaust gases to EGR assembly 900 and aninternal coolant passage 904 for flowing coolant to EGR assembly 900.

Internal exhaust passage 902 receives exhaust gases (e.g., combustedfuel and air) from one or more cylinders 118 and routes the exhaustgases through the cylinder head 114 toward EGR assembly 900. In theexample of the engine system 10 described herein with reference to FIGS.1-18, the exhaust manifold 128 is an external exhaust manifold coupledto the cylinder head 114 via fasteners (e.g., bolts) and configured toflow exhaust gases from a plurality of exhaust ports of the cylinders118 toward an external exhaust outlet 1702 (e.g., external to theinterior of the cylinder head 114 and shown by FIG. 17).

The internal exhaust passage 902 may be joined (e.g., formed together)with one or more of the exhaust ports internal to the cylinder head 114such that a portion of exhaust gases flowing from the one or moreexhaust ports does not flow through the exhaust manifold 128. Instead,the portion of exhaust gases described above may flow through theinternal exhaust passage 902 toward the EGR assembly 900 as indicated byexample exhaust flow path 916. In this configuration, the internalexhaust passage 902 receives the portion of exhaust gases directly fromthe exhaust ports of the cylinders 118. In other examples, exhaust gasesmay instead flow from one or more exhaust runners of the exhaustmanifold 128 into the internal exhaust passage 902. In such examples,the internal exhaust passage 902 may form an exhaust inlet aperture(e.g., an opening) at an exterior surface of the cylinder head 114(e.g., external to the interior of the cylinder head 114). The exhaustinlet aperture may be coupled to the one or more exhaust runners inorder to flow exhaust gases from the exhaust runners, through theexhaust inlet aperture, and into the internal exhaust passage 902. Inother examples, the exhaust manifold 128 may instead be an internalexhaust manifold (IEM) and may be included entirely within (e.g., formedwithin) the interior of the cylinder head 114. Specifically, the runnersof the IEM may be formed by interior surfaces of the cylinder head 114and may extend through the interior of the cylinder head 114 to coupleto the exhaust ports of the cylinders 118. In such examples, theinternal exhaust passage 902 may be joined with (e.g., formed togetherwith) one or more of the exhaust runners in order to receive a portionof exhaust gases from one or more of the respective cylinders 118. Inyet further examples, internal exhaust passage 902 may receive exhaustgases directly from a combination of the exhaust ports and the exhaustmanifold (e.g., via the exhaust runners).

EGR assembly 900 includes an EGR valve 905 positioned within an interior952 of a body 950 of the EGR assembly 900 and in a flow path (e.g.,exhaust flow path 916) of exhaust gases from the internal exhaustpassage 902. The EGR valve 905 is positioned downstream of an EGR inlet906 formed by an exterior surface of the body 950, with the EGR inlet906 of the body 950 directly coupled to an EGR outlet 910 of thecylinder head 114. The EGR valve 905 may be a normally closed valve andmay be moved to an opened position, a closed position, and a pluralityof positions between the opened position and closed position via a valveactuator (e.g., a solenoid, hydraulic actuator, etc.). By adjusting anamount of opening of the EGR valve 905, a flow rate of exhaust gasesfrom the internal exhaust passage 902 through the EGR assembly 900 maybe adjusted. For example, increasing the amount of opening may increasethe flow rate of exhaust gases, and decreasing the amount of opening maydecrease the flow rate of exhaust gases.

In one example, the position of the EGR valve 905 may be adjusted by anelectronic controller (e.g., computer system) of the engine system 10.The controller receives signals from the various sensors of the enginesystem 10 and employs the various actuators of the engine system 10 toadjust engine operation based on the received signals and instructionsstored on a memory of the controller. For example, adjusting a flow ofexhaust gas through the EGR valve 905 may include adjusting an actuatorof the EGR valve 905 to adjust an amount of opening of the EGR valve905. In one example, the controller may determine a control signal tosend to the valve actuator, such as an amplitude of the signal beingdetermined based on a determination of the flow rate of exhaust gasthrough the EGR valve 905. The flow rate of exhaust gas through the EGRvalve may be based on a measured flow rate, or determined based onoperating conditions such as engine speed and/or a position of the EGRvalve 905. The controller may determine the amplitude through adetermination that directly takes into account the flow rate, such asincreasing the amplitude to increase the flow rate (e.g., increase anamount of opening of the EGR valve 905). The controller mayalternatively determine the amplitude based on a calculation using alook-up table with the input being flow rate and the output being signalamplitude.

The internal coolant passage 904 may be a coolant passage positioned inparallel or in series with other coolant passages formed within thecylinder head 114 by interior surfaces of the cylinder head 114. Coolant(e.g., engine coolant) may flow within the cylinder head 114 through theinternal coolant passage 904 and toward the EGR assembly 900 as shown byexample coolant flow path 914. The coolant flows from the internalcoolant passage 904, through the body 950 of the EGR assembly 900, andinto the EGR cooler 424. Exhaust gases and coolant do not mix orconverge within the body 950 of the EGR assembly 900. The internalcoolant passage 904 forms a coolant outlet 912 at an exterior surface ofthe cylinder head 114 and the coolant outlet 912 is fluidly coupled witha coolant inlet 908 of the EGR assembly 900. In the example shown byFIG. 9, the EGR assembly 900 is directly coupled to the exterior surfaceof the cylinder head 114 at the coolant outlet 912 and EGR outlet 910such that no additional coolant or exhaust gas passages external to thecylinder head 114 are positioned between the coolant outlet 912 andcoolant inlet 908 or between the EGR outlet 910 and EGR inlet 906. Bydirectly coupling the EGR assembly 900 to the cylinder head 114 androuting exhaust gases and coolant through the cylinder head to the EGRassembly 900 in this way, an amount of coolant and/or exhaust gaspassages external to the cylinder head 114 may be reduced and a size ofthe engine system 10 may be decreased.

The EGR assembly 900 is fluidly coupled to the EGR cooler 424 such thatcoolant flowing into the EGR assembly 900 (e.g., via coolant flow path914) is routed into coolant passages of the EGR cooler 424, and exhaustgas flowing into the EGR assembly 900 (e.g., via exhaust flow path 916)is routed into a bypass passage and/or a collection volume of the EGRcooler 424 as described below with reference to FIGS. 10-12.

FIGS. 10-12 show different views of the EGR cooler 424. Specifically,FIG. 10 shows a view of an exterior of the EGR cooler 424 (e.g.,exterior surfaces formed by a body 1044 of the EGR cooler 424), FIG. 11shows a view of the EGR cooler 424 along a first cross-sectional planeparallel to the vertical axis 152 and lateral axis 154 and positioned atan inlet end 1042 of the EGR cooler 424, and FIG. 12 shows view of theEGR cooler 424 along a second cross-sectional plane parallel to thefirst cross-sectional plane and positioned at an outlet end 1040 of theEGR cooler 424. The inlet end 1042 and outlet end 1040 are positionedopposite to each other along a central axis 1030 of the EGR cooler 424.Exhaust gases may flow from the EGR assembly 900 coupled to the cylinderhead 114 (as described above with reference to FIG. 9) into a collectionvolume 1100 formed by an interior 1046 of the body 1044 via an exhaustinlet 1104 positioned at the inlet end 1042. The exhaust gases may becooled by heat transfer (e.g., transfer of thermal energy) from theexhaust gases to coolant (e.g., engine coolant) flowing through one ormore coolant passages (not shown) surrounding a perimeter of thecollection volume 1100. The coolant passages are formed within theinterior 1046 of the body 1044 and are fluidly separated from thecollection volume 1100 such that coolant and exhaust gases do not mixand/or converge within the EGR cooler 424.

Coolant may flow into the coolant passages of the EGR cooler via one ormore coolant inlets position at the inlet end 1042 of the EGR cooler424. In the example shown by FIGS. 10-12 and described herein, the inletend 1042 includes a first coolant inlet 1002, a second coolant inlet1004, and a third coolant inlet 1006 positioned radially around thecentral axis 1030 and the exterior of the EGR cooler 424. The coolantinlets (e.g., first coolant inlet 1002, second coolant inlet 1004, andthird coolant inlet 1006) are fluidly coupled with the internal coolantpassage 904 of the cylinder head 114 via the EGR assembly 900. The firstcoolant inlet 1002 is formed as an aperture within a first flange 1008of the body 1044, the second coolant inlet 1004 is formed as an aperturewithin a second flange 1010 of the body 1044, and the third coolantinlet 1006 is formed as an aperture within a third flange 1012 of thebody 1044. The first flange 1008, second flange 1010, and third flange1012 are each directly coupled to the EGR assembly 900 via a pluralityof fasteners 1014 (e.g., bolts) such that the first coolant inlet 1002,second coolant inlet 1004, and third coolant inlet 1006 are fluidlycoupled to corresponding coolant outlets of the EGR assembly 900.

In an example, coolant flows from the internal coolant passage 904 ofthe cylinder head 114, into the EGR assembly 900, and into the coolantpassages of the EGR cooler 424 via the coolant inlets described above.The coolant may absorb thermal energy from exhaust gases within the EGRcooler 424 and may then flow out of the EGR cooler 424 via a coolantoutlet 1022 in order to be recirculated within the engine system 10(e.g., cooled via a radiator fluidly coupled with the coolant outlet1022 and/or pumped back into the cylinder head 114). In one example,coolant flowing out of the EGR cooler 424 via the coolant outlet 1022may be routed via one or more external coolant passages to a heatercore. Due to the direct coupling of the coolant inlets (e.g., firstcoolant inlet 1002, second coolant inlet 1004, and third coolant inlet1006) to the body 950 of the EGR assembly 900, passages coupled to thecoolant outlet 1022 are the only external coolant passages included bythe engine system 10. By reducing the number of external coolantpassages, an overall size of the engine system 10 may be reduced.

The EGR cooler 424 includes a bypass passage 1102 configured to routeexhaust gases through the EGR cooler 424 and reduce an amount of thermalenergy transferred from the exhaust gases to the coolant flowing throughthe coolant passages. The bypass passage 1102 extends from the inlet end1042 to the outlet end 1040 within the interior 1046 of the EGR cooler424 and is positioned away from the coolant passages of the EGR cooler424. In this configuration, an amount of heat transferred from exhaustgas flowing through the bypass passage 1102 to the coolant may bedecreased relative to an amount of heat transferred to the coolant viaexhaust gas flowing within the collection volume 1100.

Exhaust gases flowing through the collection volume 1100 may flow out ofthe EGR cooler 424 via a first exhaust outlet 1016 and/or a secondexhaust outlet 1020. The first exhaust outlet 1016 and/or second exhaustoutlet 1020 may each be fluidly coupled to the intake manifold 422(e.g., via EGR passage 420 coupled to first exhaust outlet 1016) inorder to mix exhaust gases from the EGR cooler 424 with intake airflowing into the intake manifold 422 for delivery to the cylinders 118.Additionally, exhaust gases flowing through the bypass passage 1102 mayflow out of the first exhaust outlet 1016. However, in order to direct aflow of exhaust gases from the bypass passage 1102 to the first exhaustoutlet 1016, EGR cooler 424 includes a baffle 1200 surrounding aperimeter of the first exhaust outlet 1016 within the interior 1046 ofthe body 1044 of the EGR cooler 424. The baffle 1200 forms apartially-enclosed volume fluidly coupled to both of the bypass passage1102 and the collection volume 1100 and is shaped to direct exhaustgases from the bypass passage 1102 toward the first exhaust outlet 1016.By directing the exhaust gases in this way via the baffle 1200, anamount of exhaust gas recirculating into the collection volume 1100 fromthe bypass passage 1102 may be reduced.

FIGS. 13-14 show different cross-sectional views of a plurality ofintake runners included by the intake manifold 422. Specifically, FIG.13 shows a cross-sectional view of the intake manifold 422 illustratinga relative positioning of helical intake runners and non-helical intakerunners of the intake manifold 422, and FIG. 14 shows a cross-sectionalview of the intake runners coupled to intake ports of two cylinders 118of the engine system 10. A main intake inlet 1316 of the intake manifold422 is positioned along a central axis 1390 of the intake manifold 422and is fluidly coupled to each of the intake runners.

FIG. 13 shows a relative positioning of cylinders 118 in the inline-4arrangement of engine system 10. For example, a first cylinder 1350 anda fourth cylinder 1356 may be referred to herein as outer cylinders orflanking cylinders, and a second cylinder 1352 and a third cylinder 1354may be referred to herein as inner cylinders, with the inner cylinderspositioned between each of the outer cylinders along an axis 1318. FIG.14 shows an enlarged view of the inner cylinders (e.g., second cylinder1352 and third cylinder 1354).

The intake manifold 422 included by engine system 10 is an integratedintake manifold having intake runners (e.g., intake passages) formed byinterior surfaces of the cylinder head 114. The intake runners includeboth helical-shaped intake runners and non-helical-shaped intake runnerspositioned in an alternating arrangement relative to the cylinders 118.For example, first cylinder 1350 is coupled to a first non-helicalrunner 1300 and a first helical runner 1302, second cylinder 1352 iscoupled to a second non-helical runner 1304 and a second helical runner1306, third cylinder 1354 is coupled to a third helical runner 1308 anda third non-helical runner 1310, and fourth cylinder 1356 is coupled toa fourth helical runner 1312 and a fourth non-helical runner 1314.

In this arrangement, the runners coupled to the first cylinder 1350 andsecond cylinder 1352 are in an antisymmetric arrangement relative to therunners coupled to the third cylinder 1354 and fourth cylinder 1356.Specifically, the runners coupled to the first cylinder 1350 and secondcylinder 1352 form a first runner group 1370, and the runners coupled tothe third cylinder 1354 and fourth cylinder 1356 form a second runnergroup 1372, with the runners of the first runner group 1370 beingpositioned in an opposite arrangement relative to the runners of thesecond runner group 1372. For example, in outward directions (e.g.,radial directions) from the central axis 1390, the first runner group1370 and second runner group 1372 each include helical runnerspositioned adjacent to the central axis 1390 (e.g., second helicalrunner 1306 and third helical runner 1308, respectively), followedfirstly in the outward directions by non-helical runners (e.g., 1304 and1310, respectively), followed secondly in the outward directions byhelical runners (e.g., 1302 and 1312, respectively), and followedthirdly in the outward directions by non-helical runners (1300 and 1314,respectively). In embodiments in which the engine includes a differentnumber and/or arrangement of cylinders, the intake runners are arrangedin a similar arrangement (e.g., with the first runner group beingpositioned across the central axis from the second runner group andhaving an opposite arrangement of runners relative to the second runnergroup).

The helical runners (e.g., 1302, 1306, 1308, and 1312) are shaped toincrease an amount of swirl (e.g., turbulence) of intake air flowingthrough the helical runners toward the corresponding coupled cylinders118 by an amount greater than the non-helical runners (e.g., 1300, 1304,1310, 1314). In one example, the helical runners may be formed with ahelix shape (e.g., formed as passages twisting around a direction of airflow through the passages) and the non-helical runners may be formedwith a relatively cylindrical shape (e.g., smooth and not twisting). Inother examples, the helical runners and/or non-helical runners may havea different type of shape. However, in each example, the helical runnersare shaped to increase the amount of swirl of the intake air by anamount greater than the non-helical runners. In this way, an amount ofmixing of fuel and intake air within the cylinders 118 may be increasedas fuel is injected into the cylinders 118 by the fuel injectors 124,thereby increasing an efficiency of combustion of the fuel and intakeair within the cylinders 118 (e.g., decreasing an amount of uncombustedfuel/intake air within the cylinders 118).

FIG. 14 shows an enlarged view of the second cylinder 1352 and thirdcylinder 1354 depicting a relative arrangement of intake ports, exhaustports, and glow plugs coupled to the cylinders 1352 and 1354. Forexample, second cylinder 1352 includes exhaust ports 1408 and 1410,intake ports 1430 and 1432, and glow plug 1404. Third cylinder 1354includes exhaust ports 1412 and 1414, intake ports 1434 and 1436, andglow plug 1406. Intake port 1430 and intake port 1432 of second cylinder1352 are coupled with second non-helical runner 1304 and second helicalrunner 1306 (respectively) of the first runner group 1370. Intake port1434 and intake port 1436 are coupled to third helical runner 1308 andthird non-helical runner 1310 (respectively) of the second runner group1372. The glow plug 1404 coupled to second cylinder 1352 extendsdownward into the second cylinder 1352 from the cylinder head 114 at amidpoint of the second cylinder 1352. Similarly, the glow plug 1406coupled to third cylinder 1354 extends downward into the third cylinder1354 from the cylinder head 114 at a midpoint of the third cylinder1354. Other cylinders included by the engine system 10 include a similarglow plug arrangement (e.g., first cylinder 1350 and fourth cylinder1356).

In order to reduce a likelihood of fuel injected by the fuel injectors124 from impinging on the glow plugs (e.g., glow plugs 1404 and 1406)and to accommodate for the alternating arrangement of the intake runnersand the increased amount of intake air swirl as described above, thefuel injectors 124 may be positioned at different angles relative toeach other (e.g., with different spray patterns and/or directions) asdescribed below with reference to FIGS. 15-16.

FIG. 15 shows a view of two example fuel injectors coupled to the enginesystem 10, and FIG. 16 shows a relative arrangement of the fuelinjectors 124 with the engine system 10 omitted for illustrativepurposes. The position of each fuel injector is described with referenceto the axis 1318 shown by FIGS. 13-16.

A first fuel injector 1616 includes solenoid valve 1612 and is fluidlycoupled to fuel line 1504, fuel return line 1608, and first cylinder1350. A second fuel injector 1500 includes solenoid valve 1508 and isfluidly coupled to fuel line 1504, fuel return line 1512, and secondcylinder 1352. A third fuel injector 1502 includes solenoid valve 1510and is fluidly coupled to fuel line 1506, fuel return line 1514, andthird cylinder 1354. A fourth fuel injector 1618 includes solenoid valve1614 and is fluidly coupled to fuel line 1506, fuel return line 1610,and fourth cylinder 1356. Each fuel injector is shown with acorresponding axis positioned parallel to a direction of fuel flow intothe fuel injector from the corresponding solenoid valve of the fuelinjector. For example, first fuel injector 1616 is positioned along axis1604, second fuel injector 1500 is positioned along axis 1520, thirdfuel injector 1502 is positioned along axis 1522, and fourth fuelinjector 1618 is positioned along axis 1606. Axis 1604 is at a firstangle 1600 relative to axis 1318, axis 1520 is at a second angle 1516relative to axis 1318, axis 1522 is at a third angle 1518 relative toaxis 1318, and axis 1606 is at a fourth angle 1602 relative to axis1318.

The first angle 1600, second angle 1516, third angle 1518, and fourthangle 1602 may each be a different amount of angle such that the firstfuel injector 1616, second fuel injector 1500, third fuel injector 1502,and fourth fuel injector 1618 each inject fuel into their respectivecoupled cylinders at different angles relative to each other. Forexample, an amount and/or direction of swirl of intake air flowing intothe first cylinder 1350 may be different than an amount and/or directionof swirl of intake air flowing into the second cylinder 1352 due to thearrangement of the intake runners as described above with reference toFIGS. 13-14. As a result, the second angle 1516 of the second fuelinjector 1500 may be a different amount of angle than the first angle1600 of the first fuel injector 1616 so that a fuel spray pattern and/orfuel spray angle of the second fuel injector 1500 is different than afuel spray pattern and/or fuel spray angle of the first fuel injector1616. In this way, each fuel injector may be angled separately in orderto achieve a relatively equal combustion efficiency for each of thecylinders 118. In other examples, one or more of the angles of the fuelinjectors may be a same amount of angle, with at least one fuel injectorhaving a different amount of angle.

FIG. 17 shows a view of the exhaust manifold 128 coupled to the cylinderhead 114 of the engine system 10. A sealing section 1710 of a gasket1700 is positioned at an interface between the cylinder head 114 and theexhaust manifold 128 and fluidly seals the interface between thecylinder head 114 and exhaust manifold 128 (e.g., prevents leaking ofexhaust gas, oil, etc. from the location at which the exhaust manifold128 is coupled to the cylinder head 114). The gasket 1700 may include aplurality of apertures shaped to align with the exhaust ports of thecylinder head 114 and enable exhaust gases to flow from the exhaustports into exhaust runners (e.g., passages) of the exhaust manifold 128.

The gasket 1700 additionally includes a heat shielding section 1712having an upper surface 1706, a lower surface 1707, and a plurality offluid channels 1704 tapering from the upper surface 1706 to the lowersurface 1707. During conditions in which the gasket 1700 is coupledbetween the cylinder head 114 and the exhaust manifold 128, the fluidchannels 1704 are positioned vertically in-line (e.g., in a directionfrom the upper surface 1706 to the lower surface 1707) with thedirection of gravity. Fluid (e.g., oil) impinging upon the gasket 1700from locations external to the exhaust manifold 128 (e.g., locationsvertically above the gasket 1700) may be prevented from leaking onto theexhaust manifold 128 by the gasket 1700 and may instead flow into one ormore of the fluid channels 1704. The fluid channels 1704 may direct thefluid away from the exhaust manifold 128, thereby reducing a likelihoodof degradation of the exhaust manifold 128. Additionally, the heatshielding section 1712 may be formed of a material resistant todegradation at typical engine operating temperatures (e.g., steel,fiberglass, etc.) and may be configured to direct heat from the enginesystem 10 away from the exhaust manifold 128. In this way, a likelihoodof degradation of the exhaust manifold 128 may be further reduced.

FIG. 18 shows an enlarged view of the fuel pump 416 described above. Thefuel pump 416 is driven directly by the fuel pump drive gear 412, withthe fuel pump drive gear 412 in meshing engagement with the idler gear406. The fuel pump drive gear 412 includes a first toothed disc 1818fixedly coupled to a first bearing 1820 and a second toothed disc 1808rotatably coupled to the first bearing 1820. The second toothed disc1808 may be normally rotationally fixed relative to the first bearing1820. However, an operator of the engine system 10 (e.g., a user) mayrotate the second toothed disc 1808 relative to the first bearing 1820and the first toothed disc 1818 by rotating a first adjustment pin 1830of the fuel pump drive gear 412. By rotating the second toothed disc1808 relative to the first bearing 1820 via the first adjustment pin1830 (e.g., in direction 1850), a position of teeth of the secondtoothed disc 1808 may be adjusted relative to teeth of the idler gear406 (as described further below).

The idler gear 406 includes a third toothed disc 1814 fixedly coupled toa second bearing 1834 and a fourth toothed disc 1817 rotatably coupledto the second bearing 1834. The fourth toothed disc 1817 may be normallyrotationally fixed relative to the second bearing 1834. However, theoperator of the engine system 10 may rotate the fourth toothed disc 1817relative to the second bearing 1834 and the third toothed disc 1814 byrotating a second adjustment pin 1836 of the idler gear 406. By rotatingthe fourth toothed disc 1817 relative to the second bearing 1834 via thesecond adjustment pin 1836 (e.g., in direction 1850), a position ofteeth of the fourth toothed disc 1817 may be adjusted relative to teethof the third toothed disc 1814.

In the configuration described above, the first toothed disc 1818 is inmeshing engagement with the third toothed disc 1814 and the secondtoothed disc 1808 is in meshing engagement with the fourth toothed disc1817. First inset 1800 shows an example engagement of the fuel pumpdrive gear 412 with the idler gear 406. In this example, the teeth ofthe fourth toothed disc 1817 are shown in a first position relative toteeth of the third toothed disc 1814. The fourth toothed disc 1817 maybe rotated to a second position shown by second inset 1802 via rotationof the first adjustment pin 1830 in order to move the teeth of thefourth toothed disc 1817 in a direction 1844 relative to the teeth ofthe third toothed disc 1814. Moving the fourth toothed disc 1817 to thesecond position shown by second inset 1802 reduces an amount of gapbetween the teeth of the fourth toothed disc 1817 and the teeth of thesecond toothed disc 1808. By reducing the amount of gap between theteeth as described above, an amount of vibration of the idler gear 406and/or fuel pump drive gear 412 may be reduced. By reducing the amountof vibration of the gears, degradation of the fuel pump 416 may bereduced and engine torque transfer to the fuel pump 416 may beincreased.

In this way, a technical effect of reducing side loading of a fuel pumpmay be achieved, by driving a fuel pump via a series of gears thattransmit torque from a crankshaft to the fuel pump. Further, frictionallosses incurred between fuel pump and crankshaft may be reduced relativeto systems where belts and pulleys are used to couple the crankshaft tothe fuel pump. Further still, by driving the fuel pump with the seriesof gears as opposed to belts or chains, a technical effect of reducingthe distance between the crankshaft and the fuel pump may be achieved,thus reducing the size, packaging, and cost of the engine system.

Another technical effect of reducing engine size and increasingcompactness is achieved by coupling a camshaft drive belt to an idlergear driven by a crankshaft gear, and having a larger diameter than acrankshaft gear. Since the idler gear may rotate at a slower rate thanthe crankshaft, the size of the camshaft pulleys may be reduced, therebyreducing the overall size, packaging, and cost of the engine systemrelative to systems where the camshaft belt is directly coupled to thecrankshaft. The size, packaging, and cost of the engine system mayfurther by reduced by arranging the crankshaft gear, idler gear, andfuel pump drive gear in parallel with one another along the same plane.By positioning the gears in the same plane, the length of the enginesystem may be reduced relative to systems where the pump is driven by abelt or chain.

In one embodiment, a front end of an engine comprises: a first end of acrankshaft; an idler gear assembly including an idler gear and an idlerpulley, the idler gear in meshing engagement with the first end of thecrankshaft and the idler pulley coupled to and sharing a rotational axiswith the idler gear; first and second camshaft pulleys positionedvertically above the idler gear assembly; and a cam drive beltcontacting each of the first and second camshaft pulleys and the idlerpulley. A second example of the front end optionally includes the firstexample, and further includes wherein the cam drive belt does notcontact the crankshaft. A third example of the front end optionallyincludes one or both of the first and second examples, and furtherincludes wherein the front end of the engine is arranged opposite to aback end of the engine, the back end including a flywheel coupled to asecond end of the crankshaft. A fourth example of the front endoptionally includes one or more or each of the first through thirdexamples, and further includes wherein the first and second camshaftpulleys have a same diameter and are positioned adjacent to one anotherat a top side of the front end of the engine relative to a vertical axisof the engine, the top side arranged opposite a bottom side of theengine, the bottom side including an oil pan. A fifth example of thefront end optionally includes one or more or each of the first throughfourth examples, and further includes wherein the idler pulley has asmaller diameter than the idler gear and wherein the cam drive beltcontacts an outer circumferential surface of the idler pulley. A sixthexample of the front end optionally includes one or more or each of thefirst through fifth examples, and further includes wherein the first endof the crankshaft rotates in a first direction, the idler assemblyrotates in a second direction, opposite the first direction, and thefirst and second camshaft pulleys rotate in the second direction. Aseventh example of the front end optionally includes one or more or eachof the first through sixth examples, and further includes a first end ofa first camshaft directly coupled to the first camshaft pulley and asecond end of a second camshaft directly coupled to the second camshaftpulley, wherein the first and second camshafts rotate in a directionopposite a direction of rotation of the first end of the crankshaft. Aneighth example of the front end optionally includes one or more or eachof the first through seventh examples, and further includes wherein theidler gear has 63 teeth, the first end of the crankshaft has 45 teeth,and each of the first and second camshaft pulleys has 21 teeth. A ninthexample of the front end optionally includes one or more or each of thefirst through eighth examples, and further includes an oil pump drivegear drivingly coupled to the first end of the crankshaft via an oilpump drive belt, wherein the oil pump drive belt, oil pump drive gear,cam drive belt, and first and second camshaft pulleys are all arrangedin a same plane at the front end of the engine. A tenth example of thefront end optionally includes one or more or each of the first throughninth examples, and further includes a fuel pump drive gear in meshingengagement with the idler gear, the fuel pump drive gear directlycoupled to a drive shaft of a fuel pump.

In one embodiment, a method for an engine comprises: transmittingrotational motion from a crankshaft to an idler gear, the idler gearmeshing with a first end of the crankshaft via a plurality ofinterlocking teeth; rotating an idler pulley directly coupled with theidler gear via rotation of the idler gear, the idler gear and idlerpulley sharing a rotational axis; and driving rotation of first andsecond camshaft pulleys through a cam drive belt driven by the idlerpulley, the cam drive belt contacting an outer surface of the first andsecond camshaft pulleys and the idler pulley. In a first example of themethod, transmitting rotational motion from the crankshaft to the idlergear includes rotating the crankshaft in a first direction and rotatingthe idler gear in a second direction, opposite the first direction, androtating the idler pulley includes rotating the idler pulley in thesecond direction. A second example of the method optionally includes thefirst example, and further includes rotating a first camshaft directlycoupled to the first camshaft pulley in the second direction androtating a second camshaft directly coupled to the second camshaftpulley in the second direction. A third example of the method optionallyincludes one or both of the first and second examples, and furtherincludes wherein driving rotation of the first and second camshaftpulleys includes rotating the first and second camshaft pulleys at halfa speed of rotation of the camshaft. A fourth example of the methodoptionally includes one or more or each of the first through thirdexamples, and further includes wherein the idler gear, idler pulley, andfirst and second camshaft pulleys are all arranged at a front end of theengine, the front end opposite a back end of the engine including aflywheel of the engine.

In one embodiment, a system for an engine comprises: a front end,comprising: a first end of a crankshaft; an idler gear assemblyincluding an idler gear and idler pulley, the idler gear in meshingengagement with the first end of the crankshaft and the idler pulleycoupled to and sharing a rotational axis with the idler gear; first andsecond camshaft pulleys coupled to first and second camshafts,respectively; and a cam drive belt contacting each of the first andsecond camshaft pulleys and the idler pulley and not the first end ofthe crankshaft; and a back end arranged opposite the front end, the backend including a flywheel coupled to a second end of the crankshaft. In afirst example of the system, the idler pulley has a smaller diameterthan the idle gear, and the idler gear includes a greater number ofteeth than the first end of the crankshaft. A second example of thesystem optionally includes the first example, and further includeswherein the front end further comprises a fuel pump drive gear inmeshing engagement with the idler gear, the fuel pump drive geardirectly coupled to a drive shaft of a fuel pump, wherein the fuel pumpis positioned more interior to the engine than the front end of theengine. A third example of the system optionally includes one or both ofthe first and second examples, and further includes wherein the frontend further comprises an oil pump drive gear in meshing engagement witha crankshaft pulley directly coupled to the first end of the crankshaftand directly coupled to an input shaft of an oil pump, wherein an oilpump belt contacts each of the crankshaft pulley and the oil pump drivegear. A fourth example of the system optionally includes one or more oreach of the first through third examples, and further includes whereinthe front end further comprises a tensioner positioned vertically abovethe idler gear assembly and vertically below the first and secondcamshaft pulleys, where a side of the tensioner contacts an outersurface of the cam drive belt and wherein an inner surface of the camdrive belt contacts the first and second camshaft pulleys.

In an alternate representation, a system comprises: a cylinder head ofan engine; a plurality of passages extending through an interior of thecylinder head and formed by interior surfaces of the cylinder head, theplurality of passages including a first passage forming an exhaust gasoutlet at an exterior surface of the cylinder head and a second passageforming a coolant outlet at the exterior surface; and an EGR valveassembly directly coupled to the cylinder head at the exhaust gas outletand coolant outlet. In a first example of the system, the EGR valveassembly includes a coolant passage coupled directly to the secondpassage and wherein engine coolant is adapted to flow from the secondpassage in the cylinder head to the coolant passage of the EGR valveassembly.

In another alternate representation, an EGR cooler comprises: a bodyhaving an inlet end and an outlet end; an exhaust gas collection volumepositioned within an interior of the body and fluidly coupled to anexhaust outlet formed by an exterior surface of the body at the outletend; a baffle having a first end shaped to enclose a perimeter of theexhaust outlet within the interior; and an exhaust gas bypass passageextending through the interior of the body from the inlet end of thebody to the baffle at a second end of the baffle opposite the first end.In a first example of the EGR cooler, the EGR cooler further includes anexhaust gas outlet positioned at the outlet end, where the exhaust gasoutlet is fluidly coupled with the baffle.

In yet another representation, a system comprises: an intake manifoldincluding: a first end positioned opposite to a second end; a main inletaperture positioned midway between the first end and second end along acentral axis; a first intake runner positioned between the central axisand the first end; a second intake runner positioned adjacent to thefirst intake runner and between the central axis and the second end; athird intake runner positioned adjacent to the first intake runnerbetween the first end and the first intake runner; and a fourth intakerunner positioned adjacent to the second intake runner between thesecond end and the second intake runner; wherein the first intake runnerand second intake runner are each helical passages, and wherein thethird intake runner and fourth intake runner are each non-helicalpassages.

In yet another representation, a system comprises: a cylinder bankincluding a first and second plurality of engine cylinders; an intakemanifold including a plurality of helical intake runners positioned inalternating arrangement with a plurality of non-helical intake runners;a first plurality of fuel injectors coupled to the first plurality ofengine cylinders and angled in a first direction relative to acenterline of the cylinder bank; and a second plurality of fuelinjectors coupled to the second plurality of engine cylinders and angledin a second direction opposite to the first direction relative to thecenterline.

In yet another representation, a system for an intake manifold of anengine includes: four engine cylinders arranged in an in-lineconfiguration; a main intake inlet fluidly coupled to each of the fourengine cylinders and centered along a central axis of the intakemanifold, where two cylinders of the four engine cylinders aresymmetrically arranged on opposite sides of the central axis; aplurality of helical intake runners, where each of the four enginecylinders is fluidly coupled to the main intake inlet via one of theplurality of helical intake runners; and a plurality of non-helicalintake runners, where each of the four engine cylinders is fluidlycoupled to the main intake inlet via one of the plurality of non-helicalintake runners, and where the plurality of helical intake runners andplurality of non-helical intake runners have mirror symmetry across thecentral axis. In a first example of the system for the intake manifold,the system further includes a plurality of fuel injectors, where eachfuel injector of the plurality of fuel injectors is coupled to adifferent engine cylinder of the four engine cylinders and arranged at adifferent angle than other fuel injectors of the plurality of fuelinjectors. In a second example of the system for the intake manifold,the different angle of each of the fuel injectors is based on a geometryof a corresponding helical intake runner of the corresponding enginecylinder.

In yet another representation, an exhaust manifold gasket comprises: asealing section shaped to fluidly seal a coupling interface between anexhaust manifold and a cylinder head; and a heat shielding sectionhaving an upper surface, a lower surface, and a plurality of fluidchannels tapering from the upper surface to the lower surface, the fluidchannels being positioned vertically above the sealing section relativeto a direction of gravity at the coupling interface.

In yet another representation, a system comprises: a fuel pump; a fuelpump drive gear assembly coupled to the fuel pump including a firstdrive gear fixedly coupled to a first bearing and a second drive gearrotatably coupled to the first bearing and rotatable relative to thefirst bearing via a first adjustment pin; and an idler gear assemblyincluding a first idler gear fixedly coupled to a second bearing and asecond idler gear rotatably coupled to the second bearing and rotatablerelative to the second bearing via a second adjustment pin, the firstidler gear in meshing engagement with the first drive gear and thesecond idler gear in meshing engagement with the second drive gear.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A front end of an engine, comprising: afirst end of a crankshaft; an idler gear assembly including an idlergear and an idler pulley, the idler gear in meshing engagement with thefirst end of the crankshaft and the idler pulley coupled to and sharinga rotational axis with the idler gear; first and second camshaft pulleyspositioned vertically above the idler gear assembly; a cam drive beltcontacting each of the first and second camshaft pulleys and the idlerpulley; and a fuel pump drive gear in direct meshing engagement with theidler gear, the fuel pump drive gear directly coupled to a drive shaftof a fuel pump, where the fuel pump is positioned between, in adirection of the rotational axis of the idler gear, pistons of theengine and the idler gear and the fuel pump drive gear.
 2. The front endof claim 1, wherein the cam drive belt does not contact the crankshaftand wherein the idler pulley is arranged in front of the idler gear,closer to a front cover of the front end than the idler gear.
 3. Thefront end of claim 2, further comprising an oil pump drive geardrivingly coupled to the first end of the crankshaft via an oil pumpdrive belt, wherein the oil pump drive belt, the oil pump drive gear,the cam drive belt, the first and second camshaft pulleys, and the idlerpulley are all arranged in a same plane at the front end of the engine.4. The front end of claim 1, wherein the front end of the engine isarranged opposite to a back end of the engine, the back end including aflywheel coupled to a second end of the crankshaft, wherein cylinders ofthe engine are positioned in an in-line configuration, a piston of thepistons positioned within each cylinder, and wherein the fuel pump ispositioned in front of, in the direction of the rotational axis andrelative to the front end, all pistons of the engine.
 5. The front endof claim 1, wherein the first and second camshaft pulleys have a samediameter and are positioned adjacent to one another at a top side of thefront end of the engine relative to a vertical axis of the engine, thetop side arranged opposite a bottom side of the engine, the bottom sideincluding an oil pan and wherein the engine is a diesel engine.
 6. Thefront end of claim 1, wherein the idler pulley has a smaller diameterthan the idler gear and wherein the cam drive belt contacts an outercircumferential surface of the idler pulley.
 7. The front end of claim1, wherein the first end of the crankshaft rotates in a first direction,the idler gear assembly rotates in a second direction, opposite thefirst direction, and the first and second camshaft pulleys rotate in thesecond direction and wherein the fuel pump drive gear being in directmeshing engagement with the idler gear includes teeth of the fuel pumpdrive gear being in meshing engagement with teeth of the idler gear. 8.The front end of claim 1, further comprising a first end of a firstcamshaft directly coupled to the first camshaft pulley and a second endof a second camshaft directly coupled to the second camshaft pulley,wherein the first and second camshafts rotate in a direction opposite adirection of rotation of the first end of the crankshaft.
 9. The frontend of claim 1, wherein the idler gear has 63 teeth, the first end ofthe crankshaft has 45 teeth, and each of the first and second camshaftpulleys has 21 teeth.
 10. The front end of claim 1, wherein the fuelpump is a diesel fuel injection pump and is positioned vertically abovethe crankshaft and vertically below an EGR cooler.
 11. A method for anengine, comprising: transmitting rotational motion from a crankshaft toan idler gear, the idler gear meshing with a first end of the crankshaftvia a plurality of interlocking teeth; rotating an idler pulley directlycoupled with the idler gear via rotation of the idler gear, the idlergear and the idler pulley sharing a rotational axis; driving rotation offirst and second camshaft pulleys through a cam drive belt driven by theidler pulley, the cam drive belt contacting an outer surface of thefirst and second camshaft pulleys and the idler pulley; driving rotationof a fuel pump drive gear in direct meshing engagement with the idlergear, via rotation of the idler gear, the fuel pump drive gear directlycoupled to a drive shaft of a fuel pump; and adjusting an amount of gapbetween teeth of the idler gear and the fuel pump drive gear viaadjusting a relative position between teeth of a first toothed disc andteeth of a second toothed disc of a scissor gear, where the scissor gearis one of the fuel pump drive gear and the idler gear.
 12. The method ofclaim 11, wherein transmitting rotational motion from the crankshaft tothe idler gear includes rotating the crankshaft in a first direction androtating the idler gear in a second direction, opposite the firstdirection, wherein rotating the idler pulley includes rotating the idlerpulley in the second direction, and wherein the first toothed disc isfixedly coupled to a bearing of the scissor gear and the second toothdisc is rotatably coupled to the bearing.
 13. The method of claim 12,further comprising rotating a first camshaft directly coupled to thefirst camshaft pulley in the second direction and rotating a secondcamshaft directly coupled to the second camshaft pulley in the seconddirection.
 14. The method of claim 13, wherein driving rotation of thefirst and second camshaft pulleys includes rotating the first and secondcamshaft pulleys at half a speed of rotation of the first camshaft andthe second camshaft.
 15. The method of claim 11, wherein the idler gear,the idler pulley, and the first and second camshaft pulleys are allarranged at a front end of the engine, the front end opposite a back endof the engine including a flywheel of the engine and wherein the fuelpump is positioned between, in a direction of a rotational axis of theidler gear, pistons of the engine and the idler gear and the fuel pumpdrive gear, where the fuel pump is further positioned vertically abovethe crankshaft.
 16. A system for an engine, comprising: a front end,comprising: a first end of a crankshaft; an idler gear assemblyincluding an idler gear and an idler pulley, the idler gear in meshingengagement with the first end of the crankshaft and the idler pulleycoupled to and sharing a rotational axis with the idler gear; first andsecond camshaft pulleys coupled to first and second camshafts,respectively; a cam drive belt contacting each of the first and secondcamshaft pulleys and the idler pulley and not the first end of thecrankshaft; a fuel pump drive gear in direct meshing engagement with theidler gear, the fuel pump drive gear directly coupled to a drive shaftof a fuel injection pump, where the fuel injection pump is positionedmore interior to the engine than the front end of the engine andvertically above the crankshaft, the fuel injection pump positionedbetween, in a direction of the rotational axis of the idler gear,pistons of the engine and the idler gear and the fuel pump drive gear,where cylinders of the engine, each adapted to receive a piston of thepistons, are arranged inline; and an oil pump drive gear in meshingengagement with a crankshaft pulley directly coupled to the first end ofthe crankshaft and directly coupled to an input shaft of an oil pump,wherein an oil pump belt contacts each of the crankshaft pulley and theoil pump drive gear, where the oil pump belt and the cam drive belt arearranged in a same plane; and a back end arranged opposite the frontend, the back end including a flywheel coupled to a second end of thecrankshaft.
 17. The system of claim 16, wherein the idler pulley has asmaller diameter than the idler gear, wherein the idler gear includes agreater number of teeth than the first end of the crankshaft.
 18. Thesystem of claim 16, wherein each of the idler gear and the fuel pumpdrive gear are scissor gears including first and second toothed discsthat are rotatable relative to one another to adjust a relative positionof teeth of the first disc and of the second disc.
 19. The system ofclaim 16, wherein the idler pulley is arranged in front of the idlergear, relative to a front cover of the front end, the front coveradapted to cover the idler gear assembly, and wherein the idler pulley,the oil pump drive belt, and the cam drive belt are all arranged in asame plane, where the rotational axis of the idler gear is arrangednormal to the plane.
 20. The system of claim 16, wherein the front endfurther comprises a tensioner positioned vertically above the idler gearassembly and vertically below the first and second camshaft pulleys,where a side of the tensioner contacts an outer surface of the cam drivebelt and wherein an inner surface of the cam drive belt contacts thefirst and second camshaft pulleys.